Hey everyone, I posted this in the betta part of the forum but got little responce so I thought I'd try here also.

Heres the background info: i've got a 2-2.5 gal tank housing a betta. Currently I am faithful in doing roughly 50% pwc twice a week. However there always little particles that the gravel vac didnt get so I'm thinking about filters. I don't want a HOB if i can help it, I want to keep the lid on as far as I can. So the pretty much leaves a DIY sponge type filter. BUT another requirement is that it can't have a strong output or surface agitation. Thats where some hopeful engineering comes into play with the plans listed below.

hehehe how about this brain storm... alright so what I'm thinking is cut some sort of foam or sponge into a triangle(so it'll fit in the cornor, and to help it kinda blend in I'll use a color that matches my gravel), place a sort of lift tube in it about mid way to 3/4 down(possibly 3/4" diameter clear tubing so that its not too noticeable) . Above the sponge drill holes into the tube to let the water passing through the sponge escape. To cause the water to flow through the assembly use an air pump and stone incerted into the tube, the bubbles going up through the tube cause the water to rise and pass through the holes and be replaced/displaced by water elsewhere in the tank. OK so that all sounds normal to me..but thats gonna cause surface agitation right? Well what if I carried that lift tube all the way above the surface of the water? The bubbles will break the surface within the tube and not cause a lot of water movement at the surface ...right? Is this what everybody does? ha did I miss something here?

Sorry to burst your planned bubbles, but that won't work. If the tube sticks above the water surface, water isn't actually flowing up and out of the tube so isn't being replaced by water moving through the sponge.

Sorry to burst your planned bubbles, but that won't work. If the tube sticks above the water surface, water isn't actually flowing up and out of the tube so isn't being replaced by water moving through the sponge.

Thanks for the reply iamntbatman, not being argumentative I just want to understand. I'll try and explain a little more maybe. What if I put the air stone all the way down the lift tube, below holes drilled into it, like just over the sponge. Now this IS my first rodeo...I don't have experience here.. but the movement created by the bubbles seems like it would cause water to be pushed out of the holes drilled into the lift tube instead of having to go out of the top of it.

If the water is pushed by the bubbles from the air stone and is pushed out of the holes it seems like more water will come through the sponge and replace it. Again I really don't know. I may just have to try and paly with it and prove to myself that it wont work that way. Any more ideas?

That would work to a degree but probably not as well as having the actual tube below the water surface. What about using a powerhead instead of an air stone? Azoo makes a powerhead that's only 48 GPH and is less than $10:

Agree with iambatman the tube should be under water for it to work proper. Next thing ONLY buy a evry very small airpump I'm talking something like 1-2watts max otherwise it'll be wayyy too much action for this lil 2g tank there. Powerhead on that size tank I'd totally skip.

Here's also some sponges http://www.petsolutions.com/Sponge-Filters+C23.aspx the one's I use in my 10g's are the Bio foam's cause I'm simply too lazy to built them any more lol so I bought these, love them. Just take the same approach with the corner sponge as you want it, have the tube ~2" under the surface and hook it up.

On a side note what seems to work well as far as filtering the water for ya is building a java moss wall; don't ask me why/how but any tank that I have Java moss wall's in the water is wayyy clearer then others; plus it looks real nice, much better then these posters.

Oh another thought you may also wanna check petsmart, they have what they call "Betta bowl filter" and they're super small flat filters that only have 1 thin pad in it and powered by air as well and maybe 2" by 3" in size. Kinda looks like a mini heating pad but its a filter; just in case you don't wanna DIY after all

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